Nearly five years after Bernie Madoff was arrested for fraud, some of his former employees are about to go on trial in New York. The trial is expected to focus on how much the employees knew about Madoff's multibillion dollar Ponzi scheme. Jury selections gets under way today.

STEVE INSKEEP, HOST:

NPR's Jim Zarroli reports.

JIM ZARROLI, BYLINE: The five former Madoff employees all had lucrative jobs at Madoff's firm. For instance, Daniel Bonventre was director of operations in the back office, while Joanne Crupi and Annette Bongiorno managed client accounts. All five have pleaded not guilty and maintain they didn't know about the fraud taking place at the firm. And Madoff himself has backed them up in interviews from the federal prison in North Carolina where he now lives. But a lot of people are skeptical about that.

Ron Stein is president of the Network for Investor Action and Protection, which represents Madoff victims. He says many of them have trouble understanding how Madoff could have pulled off such a complex scheme by himself.

RON STEIN: So many are very anxious to see what exactly took place with this and how it is such a scam was able to evolve and capture so many people.

ZARROLI: The star prosecution witness is expected to be Frank DiPascali, Madoff's longtime chief financial officer, who pleaded guilty to fraud in 2009. Defense attorneys are expected to try to undermine his credibility by arguing that he lied to and misled employees for years about what was happening.